Hard to start my engine

[gkaplan]

Hello,
I have a 2012 DA40-XLS with about 400 hours. When the plane was new, starting it was very easy. It would usually start after one or two revolutions of the propeller. Now, I sometimes have to try 3 or 4 times before the engine will start. Once the engine has started, if I shut it down, it will restart easily. It's just the first start after not flying for about 1 week. The temperature has been consistent around 65F, but when it was new, even when the temperature was in the 30's, it was easy. Now, it is only easy after it's been running.

My start procedure is what is in the PoH:
1) Fuel pump on
2) Throttle open about half way
3) Mixture Rich for about 5 seconds; then lean
4) Throttle about 1/4 inch open
5) Fuel pump off
6) Start engine

The plane just came out of the annual inspection, so nothing was identified that was wrong. Any suggestions on what might be causing this?

Gerry

[Chris]

I'd suspect the electric fuel pump, especially if you still have the original equipment. Are you getting good fuel flow while priming the engine?

[rwtucker]

Just guessing but the fact that hot starts are easier than cold starts makes me think about timing, plugs and the start module, as well as pressure. Other things being equal cold starts should be one turn or less (mine have always been) and easy. Hot starts should require more finesse. My POH must be different than yours.

COLD
Electrical fuel pump ................... ON
Throttle ............................ 3 cm (1.2 in) forward from IDLE
Mixture control lever .................. RICH for 3 - 5 sec, then LEAN (closer to 3 seconds for me)
Throttle ............................ 1 cm (0.4 in) forward from IDLE
Ignition switch ....................... START

HOT
Electrical fuel pump ................... ON
Throttle ............................ 3 cm (1.2 in) forward from IDLE
Mixture control lever .................. RICH for 1 - 3 sec, then LEAN
Ignition switch ....................... START

I found that when I followed these procedures, especially the throttle settings to the millimeter, I got much better starts. The only departure I make is that I turn the fuel pump off after the prime on a cold start. So my cold start is actually:

MODIFIED COLD
Mixture control lever .................. RICH
Throttle ............................ 3 cm (1.2 in) forward from IDLE
Electrical fuel pump ................... ON (3-4 seconds)
Electrical fuel pump ................... OFF
Throttle ............................ 1 cm (0.4 in) forward from IDLE
Ignition switch ....................... START

What made the most difference for me was sticking to the 1 cm & 3 cm settings for cold and hot and leaving the fuel pump on for hot starts.

[gkaplan]

Robert, I was going by memory - what you wrote is what I do. But I could try the modified cold. After a week or so of no flying, the engine definitely doesn't start on the first try. Since it just came out of its annual inspection, I would think that if there were any problems with the fuel pump, etc., that it would have been identified at that time. Maybe I'm giving too much credit to the annual inspection. Once the plane starts, it runs just fine. During the start, I can definitely see fuel flow looking normal when I move the lever to rich, then back to cutoff. Anyway, I'll give this modified list a try.

[gkaplan]

I'd suspect the electric fuel pump, especially if you still have the original equipment. Are you getting good fuel flow while priming the engine?

Yes, the fuel flow seems perfectly normal during the priming stage.

[rwtucker]

The more I think about it, take a look at your Slick Start module. http://www.pilotshop.com/catalog/eppage ... fgodcMMMtA

[gkaplan]

The more I think about it, take a look at your Slick Start module. http://www.pilotshop.com/catalog/eppage ... fgodcMMMtA

I do have a SlickStart - Diamond says its been part of the DA40's standard installation for over a decade, so I wonder if it isn't working right.

[rwtucker]

You have one. Pull the upper cowling and you will see it on the port side closer to the firewall than the middle.

I read one report on a Beech where a SlickStart did not activate until the start key was activated momentarily, released, then re-activated.

[Chris B]

Hi Gerry -

Once the engine fires, does it immediately run smoothly or stumble for a few seconds?

If the latter, you may be experiencing the early symptoms of Lycoming "morning sickness." This is a long shot with only 400 hrs on the engine, but sticky exhaust valves will cause problems with cold starts. DAMHIKT...

Chris

[rwtucker]

If the latter, you may be experiencing the early symptoms of Lycoming "morning sickness." This is a long shot with only 400 hrs on the engine, but sticky exhaust valves will cause problems with cold starts. DAMHIKT... Chris

Scary thought. Is there something about our engines that makes this more likely or are sticking ewxhaust valves more traceable to engine management habits?